Among white women, obesity is positively associated with depressive symptoms across all income levels. However, among black women, no such associations are found – regardless of income. Meanwhile, among men, the link between obesity and depression appears strong for black men with high household incomes, a cross-sectional analysis of 12,220 adults suggests.

“This work underscores the importance of disentangling the association of race and [socioeconomic status] to gain a better understanding of how each operates to impact health outcomes,” wrote Caryn N. Bell, PhD, and her associates. The report is in Preventive Medicine.

The study comprised 3,755 black subjects, 55.5% of whom were women, and 8,465 white subjects, 51.8% of whom were women. They completed a detailed questionnaire as part of the 2007-2014 National Health and Nutrition Examination Survey and had a physical exam. Depressive symptoms were measured by the Patient Health Questionnaire-9 (PHQ-9), and obesity was defined as a body mass index of 30 kg/m2 or higher. About 1% of both black and white subjects had severe depressive symptoms, meaning a PHQ-9 score ranging from 20 to 27 points.

A greater percentage of black participants were obese (47.3% vs. 34.4%), and black participants were less likely to live in a household earning $100,000 per year or more (10.9% vs. 28.3%). Black participants were a bit younger (mean age 44.8 years vs. 49.2 years), and less likely to be currently married, college graduates, insured, and physically active. A higher percentage reported fair to poor health (23.9% vs. 14.6%). The differences were statistically significant.

For white women, the association between obesity and depression held across all income levels. For black women, this association was not found at any income level. For black men, the link between obesity and depression was limited to those with a household income of $100,000 or more (odds ratio, 4.65; 95% confidence interval, 1.48-14.59). And for white men, the association was limited to those with a household income of $35,000-$74,999 (OR, 1.44; 95% CI, 1.02-2.03).

The effect of race on obesity and depression has been well studied – it’s known, for instance, that the association between obesity and depression is strongest among white women – but the role of income as a modifier has not been well addressed, wrote Dr. Bell, an assistant professor in the department of African American studies at the University of Maryland, College Park, and her associates.

“Though major life-time depression is less prevalent among African Americans, those who are obese should be screened for depression at similar rates as whites, particularly high-income African American men,” Dr. Bell and her associates wrote.

As for explanations, the authors suggested that strong, antiobesity stigma “may be present among white women at all income levels,” and may drive depression regardless of how much they make.

The prevalence of depressive symptoms at specific income levels among men suggests that something other than stigma is at work. Depression among obese, middle-income white men might be tied to “an unmeasured factor like subjective social status.” Meanwhile, obese black men with high household incomes “have less income and wealth than their white counterparts” because “of various forms of structural racism. ... This may be manifested with higher rates of depression through obesity-related factors like unhealthy coping behaviors and stress,” the investigators said.

Dr. Bell and her associates cited a few limitations. One is that the study looked only at those factors among black and white people. “Results could differ with other ethnic groups,” they wrote. In addition, income was self-reported, and three-way interactions – which are tough to interpret – were used. Nevertheless, they said, the study results have key public health implications.

The study had no financial disclosures, and the investigators reported having no conflicts of interest.